_.grep.js

  var proplist = _.keys(_);
  var undef
  proplist.push(undef);
  proplist.push(null);
  proplist = proplist.concat(proplist);
  // proplist.push(proplist);
  
  _.isNewFunction = function (obj) { return typeof obj === 'function' }
  _.isA = function isA(o,c) {return o==null ? o===c : (o.constructor===c || ( _.isFunction(c) && o instanceof c));}	  

  _.isA_t = function isA(o,c) {return o==null ? o===c : (o.constructor===c || ( typeof c === "function" && o instanceof c));}	  

  _.isA_min = function isA(o,c) {return o==null ? o===c : (o.constructor===c || o instanceof c);}	  

  // select all elements that match a regex
  _.grep = function(obj,re) {
    return _.select(obj, function(s){ var s =_.isString(s)?s:new String(s); return s.match(re)   });
  };

   _.grep_t = function(obj,re) {
    return _.select(obj, function(s){ var s = (typeof s === "string")?s:new String(s); return s.match(re)   });
  };


  JSLitmus.test('_.isNewFunction()', function() {
    return _.select(proplist, function(prop) { return _.isNewFunction(_[prop]) }) 
  });

  JSLitmus.test('_.isFunction()', function() {
    return _.select(proplist, function(prop){ return _.isFunction(_[prop]) })  
  });
  
  JSLitmus.test('_.isA', function() {
    return _.select(proplist, function(prop) { return _.isA(_[prop], Function) }) 
  });

  JSLitmus.test('_.isA_t', function() {
    return _.select(proplist, function(prop) { return _.isA_t(_[prop], Function) })
  });
  
  JSLitmus.test('_.isA_min', function() {
    return _.select(proplist, function(prop) { return _.isA_min(_[prop], Function) })
  });
  
  JSLitmus.test('_.grep', function() {
    return  _.grep( proplist, /^is/ )
  });
  
  JSLitmus.test('_.grep_t', function() {
    return  _.grep_t( proplist, /^is/ )
  });

  JSLitmus.test('_.functions', function() {
    return  _.functions( _ );
  });